1. Field of the Invention
The invention concerns an InAs/GaSb superlattice infrared detector that is prepared on a GaSb or a GaAs substrate by low pressure organometaleic chemical vapor deposition.
3.about.5 .mu.m and 8.about.4 .mu.m is the two most penetrating window in the atmosphere; the optical communication for the next generation, in order to decrease the loss of transmission, will also be 3.about.5 .mu.m as its direction of development. The application of the infrared detector has a wide range of use including communications as well as night vision observation, surgery, resource exploration and etc.
2. Cross-Reference to Related Applications
The previously developed technique of InAs/GaSb superlattice, is concentrated in the area of molecular deposition method. The current molecular deposition method still has problems in its limitation of mass production. The method we employ is the low pressure organometaleic chemical vapor deposition and we successfully deposited a very ideal lattice. In addition, the research of the elements of InAs/GaSb superlattice is still in its stages of development. The structure proposed in this project is one big breakthrough in the research of the element of supperlattice.
Therefore, with the use of low pressure organometaleic chemical vapor deposition, we successfully deposited a high quality of InAs/GaSb superlattice structure, the element of which could be utilized in industrial mass production.
The appropriate range is 3.about.5 .mu.m and 8.about.4 .mu.m for photonic infrared detection.
There are many kinds of material; the element of InAs/GaSb superlattice belongs to the photonic infrared detection of normal incidence. Due to the reason that it uses sub-valence band transmission system, it provides a solution for injection of elements at an angle as well as the problem of complicated process of manufacturing. This is a great decrease on the cost of manufacturing. H.H. Chen and others reported, in 1992's Appl. Phys. Lett. of the 61.sup.st Issue pages 509-511, that InAs/GaSb superlattice has a very high rate of absorption of light. In addition, S. M. Chen and others in the 1995 IEEE Photonics Technology Lett.'s 7.sup.th Issue pages 1192-1194 and in the 1996 IEEE IEEE J. Quantum Electron.'s 32.sup.nd Issue pages 277-283 reported that through the control of the thickness of superlattice, the wavelength desired maybe attained. Therefore the InAs/GaSb superlattice element is very flexible and full of market potentials.
If without the alterations of the Fermi Energy Level but purely with the thickness control, there still could be no special level of energy transmission. Therefore, we have catered for the different wavelength (3.about.5 .mu.m and 8.about.4 .mu.m )of absorption. Different substrate materials for superlattice were used(e.g. positive GaSb and negative InAs) . The utilization of thick substrates to control the position of Fermi's Energy Level so that the required level of energy transmission may be achieved.